1. Field of the Invention
The present invention relates generally to precise time tagging of events over an imprecise link between two devices/terminals and, more particularly, to precise time tagging of events over an imprecise link between two chips which are not synchronized.
2. Description of the Related Art
The precise timing and synchronization of events over an imprecise link between two devices/terminals is a universal and scalable problem.
For example, in radio communication systems, e.g., Global Navigational Satellite Systems (GNSSs), upon reception of a broadcast radio signal, a receiver e.g., a GNSS receiver, attempts to accurately extract information from the received signal by performing an appropriate demodulation technique.
Typically, the GNSS receiver will include a front end having one or more terminals or chips that are configured to perform an initial step of the demodulation process of the received signal. For example, the front end of the GNSS receiver may include a radio frequency (RF) peripheral chip including a packetizer which packs data of the received signal into packets with a specific format, e.g., a data stream, and then transmits the packetized data to an appropriate interface that can receive and transmit packetized data. The interface may be another terminal of the front end or another chip, e.g., a digital host chip including a depacketizer.
During the demodulation process, it may be necessary for the digital host chip to identify when a change in status of the data stream occurs in the RF peripheral chip. Unfortunately, however, because there is a delay from the RF peripheral chip to the digital host chip and from digital host chip to RF peripheral chip, as these chips are typically not synchronized with one another (i.e., the internal clocks of these chips are not locked to each other) it is often difficult for the digital host chip to identify when such a change in the data stream occurs. This can decrease the efficacy in which the GNSS receiver can demodulate the received signal.
As can be appreciated, such problems can affect other types of wireless communication systems, e.g., Wi-Fi, that require precise timing and synchronization of events over an imprecise link between two devices/terminals.
Thus, there is a need for methods and systems for precise timing and synchronization of events over an imprecise link between two devices/terminals.